Multichannel Monostatic Rangefinder

ABSTRACT

The present disclosure relates to optical systems and methods for their manufacture. An example optical system includes a first substrate having a mounting surface and a spacer structure having at least one cavity. The spacer structure is coupled to the mounting surface of the first substrate. The optical system also includes a light-emitter device that is coupled to the spacer structure and a detector device coupled to the first substrate such that the at least one detector device is disposed within the at least one cavity of the spacer structure. The optical system also includes a second substrate that mounts a lens and a waveguide and is coupled to the spacer structure. The optical system also includes a shim coupled between the second surface of the spacer structure and a mounting surface of the second substrate.

BACKGROUND

Optical systems may include several elements, such as light sources,optical elements, and/or photodetectors disposed within a commonpackage.

SUMMARY

In a first aspect, an optical system is provided. The optical systemincludes a first substrate. The first substrate includes a mountingsurface. The optical system also includes a spacer structure having afirst surface and a second surface, opposite the first surface. Thespacer structure includes at least one cavity. The first surface of thespacer structure is coupled to the mounting surface of the firstsubstrate. The optical system additionally includes at least onelight-emitter device that is coupled to the second surface of the spacerstructure. The optical system further includes at least one detectordevice that is coupled to the mounting surface of the first substratesuch that the at least one detector device is disposed within the atleast one cavity of the spacer structure. The optical system alsoincludes a second substrate having a mounting surface. The mountingsurface of the second substrate is coupled to the second surface of thespacer structure. The optical system includes a shim coupled between thesecond surface of the spacer structure and the mounting surface of thesecond substrate. The optical system additionally includes at least onelens coupled to the mounting surface of the second substrate and atleast one waveguide coupled to the mounting surface of the secondsubstrate.

In a second aspect, a method is provided. The method includes forming atleast one cavity in a spacer structure. The spacer structure includes afirst surface and a second surface opposite the first surface. Themethod also includes coupling at least one detector device to a mountingsurface of a first substrate and coupling the mounting surface of thefirst substrate to the first surface of the spacer structure such thatthe at least one detector device is disposed within the at least onecavity of the spacer structure. The method additionally includescoupling at least one light-emitter device to the second surface of thespacer structure. The method further includes determining a step heightbetween a surface of the at least one light-emitter device and thesecond surface of the spacer structure. The method yet further includesselecting a shim based on the determined step height. The methodincludes coupling at least one lens and at least one waveguide to amounting surface of a second substrate and coupling the mounting surfaceof the second substrate to the second surface of the spacer structure byway of the selected shim.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 illustrates a schematic block representation of an opticalsystem, according to an example embodiment.

FIG. 2 illustrates a cross-sectional view of an optical system,according to an example embodiment.

FIG. 3A illustrates a step of a method of manufacture, according to anexample embodiment.

FIG. 3B illustrates a step of a method of manufacture, according to anexample embodiment.

FIG. 3C illustrates a step of a method of manufacture, according to anexample embodiment.

FIG. 3D illustrates a step of a method of manufacture, according to anexample embodiment.

FIG. 3E illustrates a step of a method of manufacture, according to anexample embodiment.

FIG. 3F illustrates a step of a method of manufacture, according to anexample embodiment.

FIG. 3G illustrates a step of a method of manufacture, according to anexample embodiment.

FIG. 4 illustrates a method, according to an example embodiment.

DETAILED DESCRIPTION

Example methods, devices, and systems are described herein. It should beunderstood that the words “example” and “exemplary” are used herein tomean “serving as an example, instance, or illustration.” Any embodimentor feature described herein as being an “example” or “exemplary” is notnecessarily to be construed as preferred or advantageous over otherembodiments or features. Other embodiments can be utilized, and otherchanges can be made, without departing from the scope of the subjectmatter presented herein.

Thus, the example embodiments described herein are not meant to belimiting. Aspects of the present disclosure, as generally describedherein, and illustrated in the figures, can be arranged, substituted,combined, separated, and designed in a wide variety of differentconfigurations, all of which are contemplated herein.

Further, unless context suggests otherwise, the features illustrated ineach of the figures may be used in combination with one another. Thus,the figures should be generally viewed as component aspects of one ormore overall embodiments, with the understanding that not allillustrated features are necessary for each embodiment.

I. Overview

In example embodiments, an optical system package could include severalelements including: a laser diode, one or more waveguides that conveythe light from the laser diode to one or more emission regions, anoptical element or feature that collects the light from the laser andcouples it into the waveguide, a mirror or other feature that redirectsthe light in the waveguide towards an emission direction, alight-sensitive receiver chip, and a pinhole that restricts theacceptance angle of light arriving at the light-sensitive receiver chip.

Such an optical system package could be utilized as part of a lightdetection and ranging (LIDAR) system. For example, the optical systempackage could form a compact, modular LIDAR system that could be used inmachine vision and/or perception applications. In some embodiments, theoptical system package could be used in LIDAR systems for semi- orfully-autonomous vehicles.

Specifically, an optical system could include a substrate with embeddedelectrical traces. In some embodiments, the substrate could include amultilayer organic (MLO) substrate, which could include, for example,one or more RF dielectric layers embedded between layers of otherlaminates to provide routing, shielding and bonding pads for placementof surface-mount components. Other substrate materials (e.g., FR4) andtypes (e.g., printed circuit board (PCB)) are possible and contemplatedherein.

A bottom surface of the substrate could include an electrical andmechanical interface to an underlying circuit board. In someembodiments, the electrical and mechanical interface could include aplurality of controlled-collapse solder balls that could serve toelectrically couple the substrate to the circuit board and maintain acontrollable spacing between the two surfaces.

The optical system also includes a spacer structure. The spacerstructure could include a plurality of plated through-holes and could bebonded to a top surface of the substrate. The spacer structure mayinclude a plurality of cavities, each cavity being an opening thatpasses between the two major surfaces of the spacer structure. In someembodiments, the spacer structure could be die-punched and coated with ablack copper material. Other coatings are contemplated and possible.

The optical system includes a plurality of photodetector devices, whichcould include silicon photomultipliers (SiPMs), avalanche photodiodes(APDs), or other types of photodetectors. Other embodiments couldinclude silicon or other semiconductor PIN or PN photodiodes, SPADarrays, or other high-speed photodetectors. In an example embodiment, 4or 16 SiPM detector chips (or a different number of detector chips)could be flip-chip bonded to the top surface of the substrate. Thephotodetector devices could be disposed on the top surface of thesubstrate so as to be within a cavity of the spacer structure when thespacer structure is bonded to the top surface of the substrate. In analternative embodiment, the photodetector devices could be situatedadjacent to the spacer structure when bonded to the top surface of thesubstrate.

The optical system also includes an intermediate lid. The intermediatelid may be coupled (e.g., bonded with epoxy or another adhesivematerial) to a top surface of the spacer structure. The intermediate lidmay include apertures and optically-opaque baffles that are registeredto the cavities of the spacer structure and/or the underlyingphotodetectors. In some embodiments, the intermediate lid could beconfigured to prevent light from leaking between adjacent cavities inthe spacer structure as well as between adjacent photodetector devices.

The optical system further includes one or more light-emitter devicesthat are coupled to the top surface of the spacer structure. Forexample, the light-emitter devices could include edge-emitting laserdiodes. It will be understood that other types of light-emitter devices,such as vertical cavity emitting lasers (e.g., VCSELs), light-emittingdiodes (LEDs), etc. are contemplated and possible within the scope ofthe present disclosure. The light-emitter devices could be coupled tothe spacer structure with conductive epoxy and/or high-temperaturesolder. Additionally or alternatively, the light-emitter devices couldbe wire-bonded to conductive pads on the top surface of the spacerstructure.

The optical system also includes a second substrate that functions as atop lid. The top lid could be formed from a transparent material, suchas glass, plastic, fused silica, or another transparent low-refractiveindex material. A top surface of the top lid could include anantireflective coating. Furthermore, during assembly, the top surface(and/or the antireflective coating) could be protected during assemblywith a removable polymer film (e.g., Kapton or polyimide). Optionally,an antireflective coating could be applied to a bottom surface of thetop lid.

The top lid could also include a plurality of waveguides coupled to thebottom surface of the top lid. In some embodiments, the waveguides couldbe configured to guide light emitted by the light-emitter devices usingtotal or partial internal reflection. At least some of the waveguidescould include mirror surfaces configured to redirect the guided lightout of plane and toward an external environment.

In some embodiments, the top lid could include a cylindrical rod lensconfigured to act as a fast-axis collimation lens that could couplelight from the light-emitter devices and direct at least a portion ofthe light toward the waveguides.

The optical system includes a shim (e.g., a shim ring) that is coupledbetween the top lid and the spacer substrate. The shim could have acontrolled thickness and could serve as a bonding interface between thetop lid and the spacer substrate. Additionally or alternatively, theshim could be configured to prevent light from leaking through the edgeof the glass substrate. In some embodiments, the shim could be a polymermaterial that cures or molds around the top lid. In such a scenario, theshim could hold the top lid at a fixed height and/or location relativeto the spacer substrate and other elements of the optical system.

In some embodiments, the thickness (e.g., distance between top andbottom surfaces) of the shim is selected such that respective emissionregions of the light-emitter devices (e.g., the laser diodes) arealigned to the waveguide and other optical components. Furthermore, insome examples, a diameter and/or thickness of the cylindrical rod lensis selected to maximize light coupling from the light-emitter devicesinto respective waveguides.

In some examples, the top lid could be fixed to the shim, intermediatelid, spacer structure, and/or the substrate with an adhesive, such as anepoxy. Other types of adhesives, such as adhesive films, tape, or gluesare possible and contemplated within the context of the presentdisclosure.

Furthermore, in some scenarios, the photodetectors (e.g., the SiPMchips) could include narrow-band optical filters on or beneath theirrespective top surfaces. Additionally or alternatively, in otherembodiments, the pinhole may have a narrow-band filter situated on orbehind it.

In some embodiments, electrical signals are coupled into and out of theoptical system package through solder balls disposed on a bottom surfaceof the optical system package. Some embodiments can include controllinga final height of the solder connection using controlled-collapse solderballs such as plastic core, high melting point alloy. Other methods tomaintain a controlled gap between two surfaces, such as plastic, glass,or metal spacer balls or shims either on their own or contained withinthe conductive material are possible and contemplated. Other methods ofconveying electrical signals include solder pads without solder balls,conductive adhesive, and/or solderable legs.

In some cases, electrical circuitry for providing a modulated signal tothe laser diode is located within the package. Such circuit elements caninclude a Gallium Nitride FET (GaNFET) switch and a charge storagedevice such as a ceramic capacitor or reverse-biased transistor. In someembodiments, the modulated signal could cause the laser diode to emitlaser light pulses, pulse trains, frequency-modulated continuous-wavelaser light, or laser light according to other modulation formats.

In embodiments, a conductive shield is placed around at least a portionof the optical system package chip to minimize the opportunity forundesired electrical signals to couple into the receiver circuitry.Furthermore, an acceptance angle of the pinhole and receiver combinationcould be matched to a numerical aperture of an external lens.Additionally or alternatively, an emission angle of the laser, couplingelement, waveguide, and mirror could be matched to the numericalaperture of the external lens.

Other aspects, embodiments, and implementations will become apparent tothose of ordinary skill in the art by reading the following detaileddescription, with reference where appropriate to the accompanyingdrawings.

II. Example Systems

FIG. 1 illustrates a schematic block representation of an optical system100, according to an example embodiment. In some cases, optical system100 could be utilized as a compact LIDAR system, or a portion thereof.Such LIDAR systems may be configured to provide information (e.g., pointcloud data) about one or more objects (e.g., location, shape, etc.) in agiven environment. In an example embodiment, the LIDAR system couldprovide point cloud information, object information, mappinginformation, or other information to a vehicle. The vehicle could be asemi- or fully-automated vehicle. For instance, the vehicle could be aself-driving car, an autonomous drone aircraft, an autonomous truck, oran autonomous robot. Other types of vehicles and LIDAR systems arecontemplated herein.

The optical system 100 includes a first substrate 110, which includes amounting surface 112. In some examples, the first substrate 110 could beapproximately 200 microns thick. For instance, the first substrate 110could have a thickness of between 100 to 500 microns. However, otherthicknesses are possible and contemplated. In some embodiments, thefirst substrate 110 could be a printed circuit board (PCB). In someother embodiments, the first substrate 110 could include a semiconductorsubstrate material such as silicon, gallium arsenide, or the like. Insome embodiments, the first substrate 110 could include asilicon-on-insulator (SOI) material. Alternatively, the first substrate110 could be formed from a variety of other solid and/or flexiblematerials, each of which is contemplated in the present disclosure.

The optical system 100 also includes a spacer structure 120. The spacerstructure 120 includes a first surface 122 that has an opening thatforms at least one cavity 126 in the spacer structure 120. The spacerstructure 120 also includes a second surface 124, opposite the firstsurface 122, that has an opening forming the at least one cavity 126.The first surface 122 of the spacer structure 120 is coupled to thefirst substrate 110, and in some examples, directly to the mountingsurface 112 of the first substrate 110.

As described elsewhere herein, the at least one cavity 126 could beformed in the spacer structure 120 by utilizing alithographically-defined wet or dry etch process. Other semiconductormanufacturing techniques to form the at least one cavity 126 arepossible and contemplated.

In some embodiments, the spacer structure 120 could include one or moreelectrical vias 128 that could electrically connect (not shown), forexample, structures coupled to the first surface 122 (e.g., circuitboard 190) to those coupled to the second surface 124 (e.g.,light-emitter device 130).

The optical system 100 additionally includes at least one light-emitterdevice 130. The at least one light-emitter device 130 is coupled to thesecond surface 124 of the spacer structure 120. The at least onelight-emitter device 130 could be configured to provide light pulseshaving at least one infrared wavelength (e.g., 905 nm). Otherwavelengths and wavelength ranges are possible and contemplated. The atleast one light-emitter device 130 could each include one or more laserbars or another type of light-emitting structure. In some embodiments,the light-emitter device 130 could include an InGaAs/GaAs laser diode,however other material systems are possible.

The optical system 100 yet further includes at least one detector device140. The at least one detector device 140 is coupled to the mountingsurface 112 of the first substrate 110. In some embodiments, the atleast one detector device 140 is disposed within the at least one cavity126 of the spacer structure 120. In examples, the at least one detectordevice 140 could be a silicon photomultiplier (SiPM), an avalanchephotodiode (APD), or another type of photodetector.

The optical system 100 also includes an intermediate lid 150 that iscoupled to the second surface 124 of the spacer structure 120. Theintermediate lid includes at least one aperture 152 that defines anoptical path to the at least one detector device 140 through the atleast one cavity 126 of the spacer structure 120.

The optical system 100 additionally includes a second substrate 160,which has a mounting surface 162. The mounting surface 162 of the secondsubstrate 160 is coupled to the second surface 124 of the spacerstructure 120. In some embodiments, the second substrate 160 includes amaterial that is transparent to light emitted by the at least onelight-emitter device 130.

The optical system 100 further includes at least one lens 164 coupled tothe mounting surface 162 of the second substrate 160. In someembodiments, the at least one lens 164 could be a cylindrical lens. Insuch scenarios, the cylindrical lens may be configured to collimatelight emitted by the at least one light-emitter device 130. For example,the cylindrical lens could provide fast-axis collimation of lightemitted from the at least one light-emitter device 130. Furthermore, insome embodiments, the cylindrical lens could include one or more opticalfibers.

In some embodiments, the at least one lens 164 could include materialssuch as glass (silica), polycarbonate, polyethylene, fluoride,chalcogenides, and/or other optical materials. In an example embodiment,the at least one lens 164 could be utilized to focus, defocus, direct,and/or otherwise couple the emitted light into at least one waveguide166. In some embodiments, the at least one lens 164 could beapproximately 100-200 microns in diameter. However, other diameters arepossible and contemplated. In addition, lenses that are in other shapescould be used instead of, or in addition to, the at least one lens 164.

In some embodiments, the at least one lens 164 could be coupled to themounting surface 162 with epoxy or another type of adhesive.Additionally or alternatively, the at least one lens 164 could bedisposed between at least one pair of three-dimensional alignmentstructures. In such scenarios, the at least one pair ofthree-dimensional alignment structures could be configured to secure theat least one lens 164 to a predetermined location.

The optical system 100 also includes at least one waveguide 166 coupledto the mounting surface 162 of the second substrate 160. The at leastone light-emitter device 130 is configured to emit light toward the atleast one lens 164 such that at least a portion of the emitted light isoptically coupled into the at least one waveguide 166 asoptically-coupled light.

For example, the at least one waveguide 166 could be configured toefficiently guide light along a propagation direction. For example, theat least one waveguide 166 may be configured to couple light emittedfrom the at least one light-emitter device 130. At least a portion ofsuch light may be guided within at least a portion of the at least onewaveguide 166 via total internal reflection and/or evanescent opticalcoupling.

In some embodiments, the at least one waveguide 166 includes at leastone reflective surface. In such scenarios, at least a portion of theoptically-coupled light could interact with the at least one reflectivesurface so as to be directed toward an external environment. Forexample, the at least one waveguide 166 may include one or morereflective surfaces (e.g., mirrored facets) configured to direct lightnormal to the propagation direction. In such a scenario, at least aportion of the light may be coupled out of the at least one waveguide166 via a mirrored facet.

In some scenarios, the at least one waveguide 166 could be formed from apolymeric material, such as photoresist. For example, the polymericmaterial may include SU-8 polymer, Kloe K-CL negative photoresist, DowPHOTOPOSIT negative photoresist, or JSR negative tone THB photoresist.It will be understood that the at least one waveguide 166 may be formedfrom other polymeric photo-patternable materials. The at least onewaveguide 166 could be a photo-patterned material layer that is 100-120microns thick. However, the at least one waveguide 166 couldalternatively have a different thickness.

In some embodiments, the at least one detector device 140 is configuredto receive light from the external environment via the second substrate160, the at least one waveguide 166, and the at least one aperture 152.In other words, light from the external environment could pass throughthe substantially transparent second substrate 160 and at least onewaveguide 166 as well as through an opening defined by the at least oneaperture 152 and into the at least one cavity 126 to the at least onedetector device 140.

In some embodiments, optical system 100 could also include a shim 170,which could be coupled between the second surface 124 of the spacerstructure 120 and the mounting surface 162 of the second substrate 160.

In example embodiments, the optical system 100 additionally includes acircuit board 190. In such scenarios, the circuit board 190 could becoupled to a surface of the first substrate 110 by way of a plurality ofcontrolled-collapse solder balls 180.

In some embodiments, the optical system 100 could include one or morepulser circuits 132 configured to control the at least one light-emitterdevice 130. For instance, in some embodiments, the one or more pulsercircuits 132 could be disposed on the second surface 124 of the spacerstructure 120. In other embodiments, the one or more pulser circuits 132could be located elsewhere. Additionally or alternatively, the at leastone light-emitter device 130 could be electrically-coupled to the one ormore pulser circuits 132 by way of one or more wire bonds.

FIG. 2 illustrates a cross-sectional view 200 of the optical system 100,according to an example embodiment. FIG. 2 could include elements thatare similar or identical to those of optical system 100 illustrated anddescribed in reference to FIG. 1.

For example, in some embodiments, the optical system 100 could include afirst substrate 110 having a mounting surface 112. The optical system100 could include a spacer structure 120 having a first surface 122 anda second surface 124. The spacer structure 120 could include one or morecavities 126 a-126 d.

One or more light-emitter devices 130 could be coupled to the secondsurface 124 of the spacer structure 120. The light-emitter devices 130could each include one or more light-emitting regions 131. Asillustrated in FIG. 2, the second surface 124 could include an uppersurface 124 a and a lower surface 124 b. For example, the upper surface124 a could define a first plane and the lower surface 124 b coulddefine a second plane. That is, in some embodiments, the second surface124 could include an upper surface 124 a that “steps down” to a lowersurface 124 b.

In some embodiments, detector devices 140 a-140 d could be disposedwithin the one or more cavities 126 a-126 d. For example, asillustrated, each cavity could include one detector device. Howeveralternatively, multiple detector devices and/or detector arrays could bedisposed in a single cavity. The detector devices 140 a-140 d could beconfigured to detect the light emitted by the one or more light-emitterdevices 130 after interaction with the external environment.

As additionally illustrated in FIG. 2, an intermediate lid 150 could becoupled to the second surface 124 (e.g., the lower surface 124 b) of thespacer structure 120. In embodiments, the intermediate lid 150 couldinclude a plurality of apertures 152 a-152 d, which could be disposedadjacent to the cavities 126 a-126 d. In some embodiments, the apertures152 a-152 d could have a diameter of 150 microns. However, otheraperture diameters are possible and contemplated.

In some embodiments, the plurality of apertures 152 a-152 d couldinclude holes drilled or lithographically etched through a material thatis substantially opaque to light emitted by the light-emitter devices130. In other embodiments, the plurality of apertures 152 a-152 d couldinclude optical windows that are substantially transparent to lightemitted by the light-emitter devices 130.

While FIG. 2 illustrates the intermediate lid 150 as including theplurality of apertures 152 a-152 d, it will be understood that in someembodiments, the plurality of apertures 152 a-152 d could be formed inthe spacer structure 120. For example, the spacer structure 120 couldinclude one or more holes forming the plurality of apertures 152 a-152d. In one example embodiment, plurality of apertures 152 a-152 d couldbe formed between the upper surface 124 a and the lower surface 124 b ofthe spacer structure 120.

FIG. 2 also illustrates a second substrate 160 that includes a mountingsurface 162. In some embodiments, the second substrate 160 could besubstantially transparent to light emitted by light-emitter device 130.At least one lens 164 could be coupled to the mounting surface 162 ofthe second substrate 160. Furthermore, at least one waveguide 166 iscoupled to the mounting surface 162 of the second substrate 160. Inembodiments, the at least one waveguide 166 could include reflectivesurfaces 167 a-167 d (e.g., mirrored facets).

In examples, a shim 170 could be disposed between a second surface 124of the spacer structure 120 and the mounting surface 162 of the secondsubstrate 160. In some embodiments, the shim 170 could be selected suchthat a light-emitting region 131 is disposed at a predetermined ordesired position with respect to the at least one lens 164 and/or the atleast one waveguide 166. For example, the shim 170 could be selected sothat light emitted from the light-emitting region 131 is efficientlycollected by the at least one lens 164 and efficiently optically-coupledinto the at least one waveguide 166.

While FIG. 2 illustrates shim 170 as being located near the sides of theoptical system 100, it will be understood that the shim 170 could belocated elsewhere. For example, shim 170 could be disposed between theintermediate lid 150 and the mounting surface 162 of the secondsubstrate 160. Additionally or alternatively, shim 170 could be presentin other regions of the optical system 100, for example, to provide abaffle (e.g., to prevent stray light).

The optical system 100 could additionally include a circuit board 190that could be physically coupled to the first substrate 110 by way ofcontrolled-collapse solder balls 180. Other ways to physically and/orelectrically connect the first substrate 110 to the circuit board 190are possible and contemplated, such as, without limitation, conventionalsolder balls, ball-grid arrays (BGA), land-grid arrays (LGA), conductivepaste, and other types of physical and electrical sockets.

III. Example Methods

FIGS. 3A-3G illustrate various steps of a method of manufacture,according to one or more example embodiments. It will be understood thatat least some of the various steps may be carried out in a differentorder than of that presented herein. Furthermore, steps may be added,subtracted, transposed, and/or repeated. FIGS. 3A-3G may serve asexample illustrations for at least some of the steps or blocks describedin relation to method 400 as illustrated and described in relation toFIG. 4. Additionally, some steps of FIGS. 3A-3G may be carried out so asto provide optical system 100, as illustrated and described in referenceto FIGS. 1 and 2.

FIG. 3A illustrates a step of a method of manufacture 300, according toan example embodiment. Step 300 initially includes providing a spacerstructure 120. The spacer structure 120 could include a semiconductormaterial and/or a polymeric material. Subsequently, using one or moretechniques, at least one cavity (e.g., cavities 126 a-126 d) could beformed in the spacer structure 120. That is, a first surface 122 of thespacer structure 120 could have an opening forming part of the at leastone cavity and a second surface 124 of the spacer structure 120 couldhave an opening forming part of the at least one cavity. In someembodiments, the cavities 126 a-126 d could be formed by removing atleast a portion of the spacer structure 120 using semiconductormanufacturing methods such as dry or wet etching processes. Other waysto form the cavities in the spacer structure 120 are contemplated.

In some embodiments, the formed spacer structure 120 could includevarious step or shelf-like structures that define various levels alongthe second surface 124 of the spacer structure 120. In other words, thesecond surface 124 could define two or more substantially parallelplanes having different z-values. In other embodiments, the secondsurface 124 could define a single, common plane.

FIG. 3B illustrates a step of a method of manufacture 310, according toan example embodiment. Step 310 includes coupling at least one detectordevice (e.g., detector devices 140 a-140 d) to a mounting surface 112 ofa first substrate 110. The detector devices could be mounted to themounting surface 112 using a pick and place tool and/or an adhesivematerial. In some embodiments, the detector devices could be mounted tothe mounting surface 112 in an aligned fashion so as to be withinrespective cavities 126 a-126 d of the spacer structure 120.

In some embodiments, the first substrate 110 could include asemiconductor material (e.g., silicon, gallium arsenide, etc.). In otherembodiments, the first substrate 110 could include other materials.

As described herein, the detector devices could include siliconphotomultiplier (SiPM) devices and/or avalanche photodiodes (APDs).Other types of photo-sensitive detector devices are possible.

Step 310 also includes coupling the mounting surface 112 of the firstsubstrate 110 to the first surface 122 of the spacer structure 120 suchthat the at least one detector device (e.g., detector devices 140 a-140d) is disposed within the at least one cavity (e.g., cavities 126 a-126d) of the spacer structure 120.

FIG. 3C illustrates a step of a method of manufacture 320, according toan example embodiment. Step 320 includes coupling at least onelight-emitter device 130 to the second surface 124 of the spacerstructure 120. The at least one light-emitter device 130 could includean InGaAs laser diode. However, other types of light-emitter devices arecontemplated and possible. In some embodiments, a plurality oflight-emitter devices 130 could be disposed along an axis extending“into the page” as illustrated (e.g., along the y-axis). Thelight-emitter devices 130 could include a light-emitting region 131,which could include a location of a laser bar and/or a light-emittingdiode region.

In some embodiments, the light-emitter device 130 could be coupled tothe second surface 124 of the spacer structure 120 by way of anadhesive, such as a conductive epoxy. However, other types of materialsconfigured to fix the light-emitter device 130 to the second surface 124are possible and contemplated. In some embodiments, the light-emitterdevice 130 could be positioned along a “shelf” or step along the secondsurface 124 of the spacer structure 120. However, in some embodiments,the second surface 124 could be planar (e.g., with respect to uppersurface 124 a. That is, in such scenarios, the intermediate lid 150 andthe plurality of apertures 152 a-152 d could be replaced by the spacerstructure 120, which could include a plurality of holes that form theplurality of apertures 152 a-152 d.

FIG. 3D illustrates a step of a method of manufacture 330, according toan example embodiment. Step 330 includes determining a step height(e.g., step height 134 or step height 136) between a surface (e.g., atop surface) of the at least one light-emitter device 130 and the secondsurface 124 of the spacer structure 120. As described herein,determining the step height could include using a contact or non-contactprofilimetry system or another type of imaging system.

Based on the determined step height, step 330 could include selecting ashim. The selected shim could, for example, provide a desired verticaloffset for the second substrate 160 and its associated components (e.g.,at least one lens 164 and at least one waveguide 166). In other words,the selected shim could help to position the second substrate 160 alongthe z-axis so as to align or position the light-emitter device 130 withthe at least one lens 164 and/or the at least one waveguide 166. Step330 could additionally include coupling the shim 170 to the secondsurface 124 of the spacer structure 120. As described herein, the shim170 could include a polymer material that cures or molds around the toplid. As such, the shim 170 could fix or hold the second substrate 160 ata fixed height and/or location relative to the spacer structure 120 andother elements of the optical system 100.

In some embodiments, step 330 could include coupling an intermediate lid150 to the second surface 124 of the spacer structure 120. In suchscenarios, the intermediate lid 150 includes at least one aperture(e.g., apertures 152 a-152 d) that defines an optical path to the atleast one detector device (e.g., detector devices 140 a-140 d) throughthe at least one cavity (e.g., cavities 126 a-126 d) of the spacerstructure 120.

FIG. 3E illustrates a step of a method of manufacture 340, according toan example embodiment. Step 340 includes coupling at least one lens 164and at least one waveguide 166 to a mounting surface 162 of a secondsubstrate 160. In some embodiments, the waveguide 166 could include oneor more reflective surfaces or mirror facets (e.g., reflective surfaces167 a-167 d). In some embodiments, the at least one lens 164 could beplaced using a pick and place system and fixed in place withthree-dimensional alignment structures and/or an adhesive material. Thealignment structures could be defined using photolithography. Forexample, the alignment structures could be formed with a photo-definablematerial. In yet other embodiments, the at least one lens 164 could bemaintained in position by a downward force applied by a clampingsurface.

In examples, the at least one waveguide 166 could be formed withphotolithography and other semiconductor manufacturing techniques. Theat least one waveguide 166 could be formed from glass, photoresist,SU-8, or another polymeric material. In some embodiments, the reflectivesurfaces 167 a-167 d could be formed using angled photolithography. Thereflective surfaces 167 a-167 d could be coated with a reflectivematerial, such as aluminum. However, other materials are possible andcontemplated. In an alternative embodiment, the at least one waveguide166 could alternatively be formed through embossing, micro injectionmolding, machining, UV molding, laser etching, or 3D printing, amongother possibilities. Furthermore, in some embodiments, the reflectivesurfaces 167 a-167 d could redirect the light entirely through totalinternal reflection without the need for a reflective metal layer.

FIG. 3F illustrates a step of a method of manufacture 350, according toan example embodiment. Step 350 includes coupling the mounting surface162 of the second substrate 160 to the second surface 124 of the spacerstructure 120 by way of the selected shim 170. In some embodiments, step350 could include aligning one or more of the elements with respect toone or more reference marks. Furthermore, coupling the mounting surface162 of the second substrate 160 to the second surface 124 of the spacerstructure 120 by way of the selected shim 170 could include applying anadhesive material to an interface between the mounting surface 162 andthe shim 170 and/or between the second surface 124 and the shim 170.

Upon coupling the mounting surface 162 of the second substrate 160 tothe second surface 124 of the spacer structure 120 by way of theselected shim 170, the light-emitting region 131 of the light-emitterdevice 130 could be substantially aligned with the at least one lens 164and/or the at least one waveguide 166.

FIG. 3G illustrates a step of a method of manufacture 360, according toan example embodiment. Step 360 includes coupling a circuit board 190 toa surface of the first substrate 110 by way of a plurality ofcontrolled-collapse solder balls 180. As an example, the circuit board190 could include some or all of the control circuitry operable tocontrol the various functions of the optical system 100. In someembodiments, the circuit board 190 could include a read-out integratedcircuit (ROIC), a pulser circuit, or other types of circuits.

FIG. 4 illustrates a method 400, according to an example embodiment.Method 400 may be carried out, at least in part, by way of some or allof the manufacturing steps or stages illustrated and described inreference to FIGS. 3A-3G. It will be understood that the method 400 mayinclude fewer or more steps or blocks than those expressly disclosedherein. Furthermore, respective steps or blocks of method 400 may beperformed in any order and each step or block may be performed one ormore times. In some embodiments, method 400 and its steps or blocks maybe performed to provide an optical system that could be similar oridentical to optical system 100, as illustrated and described inreference to FIGS. 1 and 2.

Block 402 includes forming at least one cavity in a spacer structure,the spacer structure having a first surface opposite a second surface.

In some embodiments, forming the at least one cavity in the spacerstructure could include lithographically-defining at least one of theopening in the first surface or the opening in the second surface. Forexample, the openings could be defined using photoresist, which mayfunction as an etch stop. Thereafter, the at least one cavity could beformed by way of a wet or dry etch process that removes or etchesportions of the spacer structure. For example, the at least one cavitycould be formed by utilizing an anisotropic dry etch. Other ways to formthe at least one cavity are contemplated and possible.

Block 404 includes coupling at least one detector device to a mountingsurface of a first substrate. In some embodiments, coupling the at leastone detector device to the mounting surface could include applying aconductive epoxy at an interface between the at least one detectordevice and the mounting surface. Alternatively or additionally, the atleast one detector could be wire bonded to one or more electrical padsdisposed on the mounting surface.

Block 404 also includes coupling the mounting surface of the firstsubstrate to the first surface of the spacer structure such that the atleast one detector device is disposed within the at least one cavity ofthe spacer structure. In some embodiments, coupling the first substrateto the spacer structure could include application of one or moreadhesive materials (e.g., epoxy). Additionally or alternatively, a waferbonding technique could be utilized.

Block 406 includes coupling at least one light-emitter device to thesecond surface of the spacer structure. In examples, coupling the atleast one light-emitter device to the second surface could includeapplying a conductive adhesive material to an interface between thelight-emitter device(s) and the second surface. Other ways to couple theat least one light-emitter device to the second surface of the spacerstructure are possible and contemplated.

Block 408 includes determining a step height between a surface of the atleast one light-emitter device and the second surface of the spacerstructure. In some embodiments, the step height could include a distancebetween the upper surface 124 a and a top surface of the light-emitterdevice 130. However, the step height could be another distance thatcould be used as a registration surface and/or location reference forthe one or more light-emitting regions 131. Determining the step heightcould include utilizing, for example, a contact profilometer, anon-contact profilometer (e.g., a Veeco Wyco system), an opticalmicroscope, a scanning electron microscope, or another system configuredto provide accurate step height measurements with an uncertainty orerror of less than 1-10 microns. Other ways to determine the step heightof the light-emitter device(s) are possible and contemplated.

Block 410 includes selecting a shim based on the determined step height.In such scenarios, the selected shim could be selected such that, uponcoupling the second substrate to the spacer structure, a respectivelaser diode region of the at least one light-emitter device ispositioned at a predetermined and/or desired location with respect tothe at least one lens. In some embodiments, the alignment of thelight-emitter device with respect to the lens (or vice versa) could beperformed by utilizing an external jig, a fixture, and/or a robot. Forexample, the alignment could be performed with a closed-loop controlsystem using light emitted from the light-emitter device. In such ascenario, the laser light could be coupled into the waveguide andemitted from the reflective surfaces and received by an alignmentdetector. As such, the closed-loop control system could adjust therelative position of the light-emitter device and the lens based on thelight received at the alignment detector. For example, the closed-loopcontrol system could be operable to adjust the relative position of thelight-emitter device and the lens so as to maximize an intensity of thereceived light.

Block 412 includes coupling at least one lens and at least one waveguideto a mounting surface of a second substrate. In some scenarios, the atleast one lens could include a cylindrical lens that is configured tocollimate light emitted by the at least one light-emitter device. Insome embodiments, the cylindrical lens could be an optical fiber.

Block 414 includes coupling the mounting surface of the second substrateto the second surface of the spacer structure by way of the selectedshim. In some embodiments, some or all of the coupling steps of method400 may include applying an adhesive material to at least one elementsbeing coupled, and/or an interface between the elements being coupled.For example, various blocks could include application of the adhesivematerial to the mounting surface of the first substrate, the firstsurface of the spacer structure, the second surface of the spacerstructure, the shim, or the mounting surface of the second substrate. Inembodiments, the adhesive material could include a conductive ornon-conductive epoxy. Other adhesive materials are possible andcontemplated. In some embodiments, some of the coupling steps of method400 could include other types of material bonding, such as wafer bondingtechniques, fastener-assisted bonding, etc.

In some scenarios, coupling various elements together could includeapplying an adhesive material to one or both of the elements andapplying a predetermined contact force (e.g., 1-100 N, or more) thatcould be maintained during a curing or drying period.

Additionally or alternatively, method 400 could include coupling anintermediate lid to the second surface of the spacer structure. In suchscenarios, the intermediate lid could include at least one aperture thatdefines an optical path to the at least one detector device through theat least one cavity of the spacer structure.

In some embodiments, the spacer structure could include at least onealignment feature. In such scenarios, method 400 could further includealigning the second substrate to the spacer structure according to theat least one alignment feature. For example, the second substrate couldinclude at least one portion that is transparent (or completely removed)so as to provide an alignment window for aligning the second substratewith the spacer structure. Other types of alignment (e.g., edge to edgealignment) are possible and contemplated.

In examples, method 400 could additionally or alternatively includecoupling a circuit board to a surface of the first substrate by way of aplurality of controlled-collapse solder balls.

Yet further, method 400 could also include forming at least onereflective facet in the at least one waveguide.

Optionally, method 400 could include coupling at least one pulsercircuit to the spacer structure and electrically connecting the at leastone pulser circuit to the at least one detector device.

The particular arrangements shown in the Figures should not be viewed aslimiting. It should be understood that other embodiments may includemore or less of each element shown in a given Figure. Further, some ofthe illustrated elements may be combined or omitted. Yet further, anillustrative embodiment may include elements that are not illustrated inthe Figures.

A step or block that represents a processing of information cancorrespond to circuitry that can be configured to perform the specificlogical functions of a herein-described method or technique.Alternatively or additionally, a step or block that represents aprocessing of information can correspond to a module, a segment, aphysical computer (e.g., a field programmable gate array (FPGA) orapplication-specific integrated circuit (ASIC)), or a portion of programcode (including related data). The program code can include one or moreinstructions executable by a processor for implementing specific logicalfunctions or actions in the method or technique. The program code and/orrelated data can be stored on any type of computer readable medium suchas a storage device including a disk, hard drive, or other storagemedium.

The computer readable medium can also include non-transitory computerreadable media such as computer-readable media that store data for shortperiods of time like register memory, processor cache, and random accessmemory (RAM). The computer readable media can also includenon-transitory computer readable media that store program code and/ordata for longer periods of time. Thus, the computer readable media mayinclude secondary or persistent long term storage, like read only memory(ROM), optical or magnetic disks, compact-disc read only memory(CD-ROM), for example. The computer readable media can also be any othervolatile or non-volatile storage systems. A computer readable medium canbe considered a computer readable storage medium, for example, or atangible storage device.

While various examples and embodiments have been disclosed, otherexamples and embodiments will be apparent to those skilled in the art.The various disclosed examples and embodiments are for purposes ofillustration and are not intended to be limiting, with the true scopebeing indicated by the following claims.

What is claimed is:
 1. An optical system comprising: a first substrate,wherein the first substrate comprises a mounting surface; a spacerstructure, wherein the spacer structure comprises a first surface and asecond surface, opposite the first surface, wherein the spacer structurecomprises at least one cavity, wherein the first surface of the spacerstructure is coupled to the mounting surface of the first substrate; atleast one light-emitter device, wherein the at least one light-emitterdevice is coupled to the second surface of the spacer structure; atleast one detector device, wherein the at least one detector device iscoupled to the mounting surface of the first substrate such that the atleast one detector device is disposed within the at least one cavity ofthe spacer structure; a second substrate, wherein the second substratecomprises a mounting surface, wherein the mounting surface of the secondsubstrate is coupled to the second surface of the spacer structure; ashim coupled between the second surface of the spacer structure and themounting surface of the second substrate; at least one lens coupled tothe mounting surface of the second substrate; and at least one waveguidecoupled to the mounting surface of the second substrate.
 2. The opticalsystem of claim 1, further comprising an intermediate lid, wherein theintermediate lid is coupled to the second surface of the spacerstructure, wherein the intermediate lid comprises at least one aperturethat defines an optical path to the at least one detector device throughthe at least one cavity of the spacer structure.
 3. The optical systemof claim 1, wherein the at least one light-emitter device is configuredto emit light toward the at least one lens such that at least a portionof the emitted light is optically coupled into the at least onewaveguide as optically-coupled light.
 4. The optical system of claim 3,wherein the at least one waveguide comprises at least one reflectivesurface, and wherein at least a portion of the optically-coupled lightinteracts with the reflective surface so as to be directed toward anexternal environment.
 5. The optical system of claim 1, wherein thesecond substrate comprises a material that is transparent to lightemitted by the at least one light-emitter device.
 6. The optical systemof claim 5, wherein the at least one detector device is configured toreceive light from an external environment via the second substrate, theat least one waveguide, and the at least one aperture.
 7. The opticalsystem of claim 1, further comprising a circuit board, wherein thecircuit board is coupled to a surface of the first substrate by way of aplurality of controlled-collapse solder balls.
 8. The optical system ofclaim 1, wherein the at least one lens comprises a cylindrical lens,wherein the cylindrical lens is configured to collimate light emitted bythe at least one light-emitter device.
 9. The optical system of claim 8,wherein the cylindrical lens comprises an optical fiber.
 10. The opticalsystem of claim 1, further comprising one or more pulser circuitsconfigured to control the at least one light-emitter device, wherein theone or more pulser circuits are disposed on the second surface of thespacer structure, and wherein the at least one light-emitter device iselectrically coupled to the one or more pulser circuits by way of one ormore wire bonds.
 11. A method comprising: forming at least one cavity ina spacer structure, wherein the spacer structure comprises a firstsurface and a second surface opposite the first surface; coupling atleast one detector device to a mounting surface of a first substrate andcoupling the mounting surface of the first substrate to the firstsurface of the spacer structure such that the at least one detectordevice is disposed within the at least one cavity of the spacerstructure; coupling at least one light-emitter device to the secondsurface of the spacer structure; determining a step height between asurface of the at least one light-emitter device and the second surfaceof the spacer structure; selecting a shim based on the determined stepheight; coupling at least one lens and at least one waveguide to amounting surface of a second substrate; and coupling the mountingsurface of the second substrate to the second surface of the spacerstructure by way of the selected shim.
 12. The method of claim 11,further comprising: applying an adhesive material to at least one of themounting surface of the first substrate, the first surface of the spacerstructure, the second surface of the spacer structure, the shim, or themounting surface of the second substrate.
 13. The method of claim 11,further comprising: coupling an intermediate lid to the second surfaceof the spacer structure, wherein the intermediate lid comprises at leastone aperture that defines an optical path to the at least one detectordevice through the at least one cavity of the spacer structure.
 14. Themethod of claim 11, wherein the spacer structure comprises at least onealignment feature, wherein the method further comprises aligning thesecond substrate to the spacer structure according to the at least onealignment feature.
 15. The method of claim 11, further comprising:coupling a circuit board to a surface of the first substrate by way of aplurality of controlled-collapse solder balls.
 16. The method of claim11, further comprising forming at least one reflective facet in the atleast one waveguide.
 17. The method of claim 11, wherein the selectedshim is selected such that, upon coupling the second substrate to thespacer structure, a respective laser diode region of the at least onelight-emitter device is positioned at a desired location with respect tothe at least one lens.
 18. The method of claim 11, wherein the at leastone lens comprises a cylindrical lens, wherein the cylindrical lens isconfigured to collimate light emitted by the at least one light-emitterdevice.
 19. The method of claim 18, wherein the cylindrical lenscomprises an optical fiber.
 20. The method of claim 11, furthercomprising: coupling at least one pulser circuit to the spacerstructure; and electrically connecting the at least one pulser circuitto the at least one detector device.